FIG. 8 shows a conventional fuel pump. In this fuel pump, a cylindrical housing 104 encloses a pump section 101 and a motor section 102. The motor section 102 is provided with an armature 106 and a magnet 105. FIG. 9 schematically shows a cross-section of the armature 106. The armature 106 is provided with a shaft 107, a core 111 fixed to the shaft 107, coils 119 wound around the core 111, and a commutator 108 for supplying current to the coils 119. In FIG. 9, the commutator 108 is shown as separated from the core 111 and the coils 119. However, the core 111, the coils 119, and the commutator 108 are in fact formed in an integral manner. A pair of bearings 110 and 113 is provided in the vicinity of both ends of the shaft 107, these supporting the shaft 107 in a manner allowing the rotation thereof. The magnet 105 is located so as to surround the armature 106.
As shown in FIG. 8, a lower end of the shaft 107 engages with the pump section 101, thereby rotating the pump section 101.
FIG. 10 shows a cross-sectional view along the line X—X of FIG. 9. A plurality of slots 114 (eight slots in this case) are provided in the core 111, each coil 119 being wound around four slots 114. In this specification, when one coil 119 that has passed a first slot returns to a (1+Y)-th slot, this will be referred to as the coil 119 having been wound around the Y slots. When the coils 19 are wound around four slots 114 in the core 111 that has eight slots, the coils 119 pass the vicinity of the shaft 107. As shown in FIG. 9, the coils 119 project in an axial direction from both axial end faces 11a and 111b of the core 111, and the coils 119 that project from the end faces 111a and 111b make contact with the shaft 107.